Percussive tool



3 Sheets-Sheet 1 Filed Feb. 9, 1955 June 39, 1936. RlCHARDS 2,046,210

PERCUSSIVE TOOL June 30, 1936.

H. RICHARDS PERCUSSIVE TOOL Filed Feb. 9, 1955 5 Sheets-Sheet 3 m w w M Patented June 30, 1936 tlsiiiE STATES PATENT OFFICE PERCUSSIVE TOOL British company Application February 9, 1935, Serial No. 5,803 In Great Britain March 5, 1934 2 Claims.

This invention relates to percussive tools such as chippers and hammers, and preferably to the kind in which blows are imparted to the tool on the release of a spring which is compressed by coacting cams one or more times in the revolution of a driven shaft.

Portable percussive tools as now constructed are both bulky and expensive and in consequence are not to be found in such general use as their utility would otherwise ensure. On the other hand such a tool as a portable electric, pneumatic or other drill is to be found in almost every engineering workshop owing to the fact that, comparatively, it is both cheap and light in weight.

One of the objects therefore of the present invention is to enable such a tool to be cheaply and easily convertible, as occasion requires, into a percussive tool of the same or similar portability and in such a manner that it is as easily reconvertible when again required to function as a drill.

Broadly the present invention consists of a de-- Vice in the form of a detachable unit which may be substituted for a portion of a conventional rotary tool such as the gear box of a portable electric or other drill so as to convert such rotary tool into a percussive tool.

A device according to one embodiment of this invention comprises a. casing which is adapted to be substituted for the gear-box or chuck-carrying portion of a portable electric drill and such casing contains a spindle corresponding to the spindle of the electric drill which carries the chuck or other tool holder. This spindle which is both reciprocable and rotatable is provided at its upper end with a toothed wheel which meshes with a pinion of greater width to allow for the reciprocating movement of the aforesaid spindle. On the lower end of the spindle is formed or fitted a face cam which co-acts with an equivalent fixed cam to impart to the spindle the required reciprocable movement.

In order that the invention may be clearly understood and carried into effect such an embodiment will now be described by aid of the accompanying drawings in which:

Fig. 1 is a perspective view showing in part section a detachable unit according to this invention fitted to the end of a conventional electric drill in replacement of the usual gear-box or chuck carrying portion.

Fig. 2 is a longitudinal section through the unit to a slightly larger scale than Fig. 1.

Fig. 3 is an end elevation of Fig. 2.

Fig. 4 is a perspective view of a portion of the unit hereinafter to be described showing the same detached from the main casing.

In the embodiment illustrated the unit according to the present invention is shown fitted to a standard portable electric drill, I, having a handle 5 2 at one end embodying the usual motor control switch 3, the motor (not shown) being housed in the main casing 4. The armature shaft also not shown is fitted with a toothed pinion 5, which pinion forms the driving connection to the unit.

The forward end of the casing 4 is adapted detachably to receive the unit which is noted generally by the numeral 6.

The unit in the form illustrated comprises a casing 1 which is secured to the main casing 4 of the drill by bolts 8. A portion of the casing I is threaded as at To to receive a hollow metal cap I4 which is correspondingly threaded at one end for the purpose. The outer end of the cap I4 is threaded internally to receive a boss I3 forming part of a face cam I5, having high and low portions I5a and I5b.

To prevent the cam from becoming loose during use the coacting threads in the cap and on the boss are left handed. This construction permits the cam to be removed at will for renewal or other purpose.

Co-acting with the fixed cam is a further face cam I6 which is also provided with high and low portions lBa and I6?) corresponding to the portions |5a and I5!) of the cam I5. This cam I6 is carried by, and secured to one end of a sleeve I! with which it is rotated. The cams I5 and I6 are normally kept in contact with each other by means of a spring 2|, which spring is of such a diameter that it can be slipped over the sleeve I'I, one end of it being supported by the bearing I8, the other end abutting against the rear of the cam I6.

Rotary movement is imparted to the sleeve I1 40 and cam I8 from the motor, through a toothed wheel I9 which is mounted upon the upper end of the sleeve, said wheel meshing in turn with a double width pinion 20. The pinion 20 is mounted upon the upper end of a shaft 22 carried in a hearing 22a formed in the casing I. Also mounted on this shaft is a toothed wheel 23 which engages with and consequently is driven by the main driving pinion 5 aforementioned.

This rotary movement of the sleeve l1 and cam I6 is transformed into a reciprocating movement in consequence of the rotation of the cam I6, the high portions Ilia thereof co-aoting with the high portions Ilia of cam I5 whereupon the sleeve I! and cam I6 are thrust back against the spring 2 I, the continued rotary motion of the cam l6 bringing the cams into their normal position again. When this position is reached the compressed spring will cause the cam l6 and with it the sleeve 51, the upperend of the shank bearing against the inner end of the recess when the sleeve ll is'in the lowered position. In operation and when the motor is switched on, the pinion 5 transmits motion to the shaft 22 through the toothed wheel 23. This in turn causes rotation of the pinion 20 and through it the wheel it. This wheel in turn drives the sleeve ll and associated cam l6. B-y' means a series of rapid blows is imparted'to the upper end of the shank l2 and through it to a positioned tool 9. a *Whena hole is being cut or drilled in brickwork it is desirable to impart a turning or intermittent ratchet wheei 25 which is securely mounted on' the tool holder Iii, A stop 26 is provided to hold the ratchet wheelagainst movement in the re verse direction.

"During a riveting, caulking or similar operation this intermittent rotation of the tool may notice desirable, and. therotary motion can be ithrownj out of action when required by releasing the spring Elirom the pawl, such pawl can'then be turned out of engagement with the ratchetwheel.

What I claim is:

1. A'detachable unit. for converting, a motor. driven rotary tool such asla portable drill haying.

a main casing into a percussive tool comprising a cap to fit detachably the forward. end of the case.- ing of the rotary tool to be converted, a spindle;

reciprocably and rotatably mounted therein, a, face cam on the outer end of said. spindle, afure ther and stationary face cam disposed so asto coact with said former face cam to impart are-- ciprocating motionto thelspindle a spring tending to hold the spindle in its outermost position,

said. spindle havinga recess extending; partially up its length, said aligned apertures in recess to receive in slidable engagement the upper recess being coaxial with, the face camsto; permit the r portion'of the shank of a tool holder, a toothed wheel on the inner end of the spindle, means for rotating said spindle from the motor spindle of the tool to be converted comprising a double width pinion meshing with the toothed wheel on the inner end of the spindle and permitting the spindle to reciprocate without interruption of the drive, said double width pinion being driven from a pinion on the motor spindle of the tool to be converted through a toothed wheel arranged coaxially with the double Width pinion, the arrangement being such that rotation of the said motor spindle imparts a combined rotary and reciproeating motion to the aforesaid spindle relatively to the shank of the tool holder, the upper end of which is subjected to a series of blows applied by the inner end of the recess in the spindle to the opposing en d of the shankof the tool holder by the action of the spring in returning the reciprocating spindle after each inward movement imparted tothe spindle by the coacting face cams.

2. A detachable 'unit for converting a motor.

a driven rotary tool suchasia portable drill having a main easing into a percussive toolcomprising a cap to fit detachably the forwardend of the casing of therotary tool to be converted, a spindle reciprocably and rotatably mounted therein, a facef'cam on the outer end of said spindle, a further and stationary; face cam disposed so as. to

' coact with said former face cam to impart a reciprocating motion to the spindle, a spring tending to hold the spindle in its outermost position, said spindle having are cess extending partially up its length, said recess" being coaxial with aligned aperturesin the face cams to permit the verted through a toothed, wheel arranged coax ially with, the double width pinion, meansderix ing its motion from a. spindle on. which is mounted the double width pinion for. imparting an. inter mittent rotation to, the tool holder, the arrange ment being such, thatrotat-ion of the said motor spindleimparts fa, combinedrotary and reciprocat ing, motion; to the-aforesaid spindle relatively to the'fsha'nkl of the tool holder, the upper end-of which is'subjected to a series, of blows applied as the, tool holder intermittently.v rotated, by the innerjend of therecessinthe spindle; tothe opposing end of theshank of, the tool, holder by theaction of the springinretunning thereciprocating spindle after each inward inovementimparted by the coaoting facecams,

HARRY: RICHARDS, 

